1) Field
Provided is a solar light concentration plate with high concentration efficiency and wavelength separation.
2) Description of the Related Art
A main energy source that is currently used is a fossil fuel such as coal and petroleum. However, continued use of the fossil fuel causes problems such as global warming and environmental pollution as well as resource exhaustion. Accordingly, use of renewable energy sources that do not cause environmental pollution such as solar light, tidal power, wind power, and geothermal heat has been suggested as an alternative energy source for replacing the fossil fuel.
Among the renewable energy sources, technology of converting the solar light into electricity is most widely used. Various materials and devices are being developed for the efficient conversion of the solar light into electricity, and for example, recently suggested technology based on the multi-layered p-n junction structure and III-V Group materials accomplishes light conversion efficiency of about 40%.
Furthermore, the solar light can be directly used instead of being converted into electricity. For example, direct use of the solar light as an indoor illumination by collecting the solar light by a light-collecting device installed on a rooftop of a building and transmitting the solar light inside the building using light guide has been suggested. The direct use of the solar light transmitted from the rooftop as an indoor illumination may greatly reduce electricity consumption. However, in general, natural lighting is insufficient to be used inside the building and thus artificial illuminations are used even in the daytime.
Therefore, efficient light concentration is the core technology that can be applied to various fields that utilize the solar light. A currently-available light concentration plate usually includes large number of silicon photoelectric conversion devices, thereby having a large area which may not be suitable for a mass production due to high cost.
Therefore, it has been suggested that an optical device such as lens is used for focusing the solar light on a photoelectric conversion device to increase an amount of light in a given area and to reduce a size of a photoelectric conversion device, and a prism or a diffraction lattice is used for separating wavelengths so as to utilize a photoelectric conversion device suitable for each wavelength.
However, the above-described technology may increase a space of the light concentration plate in a direction toward the solar light. For a concentration system using a lens or a hyperbolic mirror, a photoelectric conversion device is spaced apart from the lens or the mirror by a focal distance, and thus an additional space for the focal distance may be required by the system. In the case of a prism, a distance for spatially separating light according to wavelengths may be required. The above mentioned spatial limitations may make it hard to implement a photovoltaic power generation system.